Directory of U.S. Military Rockets and Missiles
Appendix 4: Undesignated Vehicles
Copyright © 2004 Andreas Parsch

Atlantic Research Iris

The Iris sounding rocket was built by Atlantic Research under contract from the rocket group of the Naval Research Laboratory (NRL). It was designed to combine the smooth acceleration profile of the liquid-fueled Aerobee with the simpler operation of solid-propellant rockets. When NRL's rocket group was transferred to NASA, the Iris became a NASA program. The first launch of the rocket occurred on 22 July 1960.

Photo: Richard Morrow, via Peter Alway
Iris (booster detached)

The Iris was fired from a launch tower, which stabilized the vehicle until the speed was high enough for the fins to become effective. A booster consisting of 7 clustered solid-fueled rockets provided a the initial accleration, and fell free before the Iris left the tower. With a payload of 45 kg (100 lb), the sounding rocket could reach an altitude of 320 km (200 miles). However, the Iris was apparently not regarded as a standard tool, because only four Iris rockets were launched by NASA (the last one in May 1962) with aeronomy payloads.

The U.S. Navy used the Iris rocket in the Hydra-Iris project. This vehicle was a modified three-finned Iris boosted by three Sparrow motors. It was launched from a floating, immersed sea platform. The advantage of this method was that the sounding rocket could be fired from any spot in the open ocean without the risk of a ship-board rocket launch. Between 10 August 1964 and 3 November 1968, eight Hydra-Iris rockets were launched, two of which failed. The payloads included magnetospheric, ionospheric and XR astronomy experiments.

Photo: via Jane's


Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for Iris:

Length (w/o booster)6.05 m (19 ft 10.1 in); booster: 1.03 m (3 ft 4.6 in)
Diameter30.5 cm (12 in)
Finspan1.20 m (47.1 in)
Weight510 kg (1130 lb)
Speed8400 km/h (5200 mph)
Altitude320 km (200 miles)
PropulsionBooster: 7x solid-fueled rocket; 12 kN (2700 lb) each for 0.8 s
Sustainer: Solid-fueled rocket; 20 kN (4510 lb) for 46 s

Main Sources

[1] Peter Alway: "Rockets of the World", Saturn Press, 1999
[2] Frederick I. Ordway III, Ronald C. Wakeford: "International Missile and Spacecraft Guide", McGraw-Hill, 1960
[3] John W.R. Taylor (ed.): "Jane's all the World's Aircraft 1969-70", Jane's, 1969
[4] Jonathan McDowell: Launch Vehicles Database

Back to Directory of U.S. Military Rockets and Missiles, Appendix 4

Last Updated: 28 November 2004